A “cap without additional seal” is intended to refer to a cap with no attached seal, which permits a tight closure of the opening of a neck of a container storing a liquid for example, without the need for a seal such as a foam disk placed under the cap's closure disc, or an injected or moulded strip acting as an O-ring seal. To receive this type of seal, prior art caps are typically provided with a groove disposed under the closing disc for insertion of the seal therein. The pressure exerted by the tension ring or the anchoring system during manufacturing of the cap compresses the seal against the upper surface of the neck of the container to provide the desired tightness.
As mentioned above, the present invention relates to a cap which ensures excellent tightness without having such an attached seal.
Prior art caps without additional seal do already exist. By way of non-limitative examples, one may refer to the following United States patents: U.S. Pat. No. 3,325,033 (WEATON) in 1967; U.S. Pat. No. 3,815,771 (MARKS) in 1974; U.S. Pat. No. 4,106,653 (MARTINELLI) in 1978; U.S. Pat. No. 4,416,383 (FRAHM et al.) in 1983; U.S. Pat. No. 4,560,077 (DUTT) in 1985; U.S. Pat. No. 4,884,707 (CRISCI) in 1989; U.S. Pat. No. 4,645,088 (MENICHETTI) in 1987; and U.S. Pat. No. 4,905,852 (ZUMBUHL) in 1990.
These above-listed patents describe caps which do not need an additional seal in as much as they are provided with annular sealing lips and/or teeth (or ridges, protrusions) which are located under the closing disc, at the periphery of the cap or on its peripheral skirt, so as to find support on contact with the neck of the container and thereby provide the desired tightness. Such caps are designed for being directly connectable to recesses specifically provided for such purpose on the external surface of the container's neck.
If all the caps without additional seal known to the Applicant seem to work, it nevertheless remains that there exists a problem when the container to be closed is large, as it is the case for water containers of three, four or five gallons such as those used in upside down position in water distribution fountains. It is indeed difficult to obtain proper tightness with these kinds of containers, especially during their transportation. It is also difficult to obtain a good impermeability, tightness and hermetical effect required to insure that the purity of the container's content remains unaffected. Good impermeability is important to insure maintenance of purity. The use of caps made of one material, that is, without any seal, is also important in order to obtain this desired impermeability. One can understand here that the handling of the containers for storage and/or delivery purposes typically causes the liquid or water stored inside the container to move, which can create a strong surf or backwash effect. It also appears that the placement of the container in a reverse position, onto a distribution fountain for example, causes pressure to be exerted on the cap. This is because typical liquid flow out of the container gets replaced by air, the air having a pressure which accounts for the transfer by gravity. The atmosphere also exerts an external pressure which varies with environmental or metrological conditions such as temperature and pressure. It is the difficult equilibrium between internal and external container pressure that saves prior art caps from leaking; the balance must thus be well controlled.
In accordance with an object of the present invention, there is thus herein described a cap without additional seal which addresses the above-noted needs and prior art shortcomings, in terms of impermeability, tightness and hermetical effect.